For most people they need a significant diet change to see any effective changes.
That's true for weight loss. It's less true for health. Increased activity level with calorie intake also increasing so that there is no net weight loss often still results in better fitness and health and lower body fat. Its often far from ideal,especially for people who start off obese who will still probably hit an equilibrium at an unhealthy body fat level, but its still quite possible to.achieve significant improvements.
Also if you're fat your joints are going to kill you if you do things like job or ride bike. Using weight machines are much more effective and comfortable for a fat person.
> Don't bother with cardio - you're fat enough that lifting weights is going to do more than enough. Cardio is boring and just improves your cardiovascular system.
Any "advice" that says "just improves your cardiovascular system" (that's your HEART) should not be targeted at someone who claims to be overweight and wanting to get healthier.
What the hell kind of health plan goes from literally no exercise activity to "hey brah, do you even lift?"